1. Field
This disclosure relates generally to techniques for performing wellsite operations. More specifically, the present invention relates to techniques, such as blowout preventers (BOPs) and related devices, for controlling leaks at a wellsite.
2. Background of the Related Art
Oilfield operations are typically performed to locate and gather valuable downhole fluids. Oil rigs may be positioned at wellsites, and downhole tools, such as drilling tools, may be deployed into the ground to reach subsurface reservoirs. Once the downhole tools form a wellbore to reach a desired reservoir, casings may be cemented into place within the wellbore, and the wellbore completed to initiate production of fluids from the reservoir. Casing, pipes or other tubing may be positioned in the wellbore to enable the passage of subsurface fluids to the surface. During wellsite operations a blowout preventer (BOP) may be placed at a wellhead to control pressure from the wellbore.
Leakage of subsurface fluids may pose a threat if released from the wellbore. Equipment, such as a BOP, may be positioned about the wellbore to form a seal with and/or sever pipes therein to prevent leakage of fluid as it is brought to the surface. In some cases, the BOPs employ rams and/or ram blocks that seal and/or sever tubing from the wellbore. Some examples of ram BOPs and/or ram blocks are provided in U.S. patent application Ser. No. 12/838,701, U.S. Pat. Nos. 4,647,002, 6,173,770, 5,025,708, 7,051,989, 5,575,452, 6,374,925, 2008/0265188, 5,735,502, 5,897,094, 7,234,530 and 2009/0056132. Some BOPs have bonnets as described, for example, in U.S. Pat. Nos. 5,897,094 and 7,044,430.
Despite the development of techniques relating to rams and/or ram blocks, there remains a need to provide advanced blowout preventer techniques. The present invention is directed to fulfilling these needs in the art.